Clapper seal for check valves

ABSTRACT

A check valve has a clapper pivotally mounted inside of a flow passage which clapper is formed by investment casting. The clapper of the check valve will only allow fluid flow in one direction. The face of the check valve has an annular groove formed therein and a recessed center portion. After a base surface is cut in the backside of the clapper, a molded rubber seal is formed on the face of the clapper with the seal extending from the annular groove with raised annular surfaces and a web covering the center portion. Upon receiving reverse flow through the check valve, the clapper will immediately close and seal against a valve surface. The raised annular surfaces deform into the annular recess therebetween allowing metal-to-metal contact between the clapper and valve surface, while simultaneously maintaining a good rubber seal contact.

BACKGROUND OF THE INVENTION

The present invention relates to check valves and, more particularly, toclappers and clapper seals for check valves. The clapper is formed byinvestment casting thereby requiring only one cut for a base surface.Thereafter, a molded rubber seal is formed on the face of the clapper.The molded rubber seal has a raised annular portion and a complete webinside of the raised annular portion to prevent fluids from seepingbehind the seal. The present invention is directed toward an improvedclapper and seals for check valves as shown in U.S. Pat. No. 3,068,903,which patent is hereby incorporated by reference.

BRIEF DESCRIPTION OF THE PRIOR ART

Prior to the present invention, many different types of check valveshaving clappers and clapper seals have been devised. However, to preventreverse fluid leakage around the clapper of the check valve at both lowand high pressures, very expensive clappers and clapper seals had to beutilized. For example, in Frye (U.S. Pat. No. 3,348,569), the clapperhad to be formed in two separate parts with the seal held therebetweenhaving a postive gravity bias on the clapper.

Other prior art required smoothly machined surfaces on the clapper withthe seal being held in the valve body. A typical such example is foundin Scaramucci (U.S. Pat. No. 3,363,650); however, the clapper as shownin Scaramucci was expensive to manufacture and machine because of itscurved sealing surface. Also, a separate sealing ring holding thesealing element required considerable machining, as well as the seatingportion of the valve and the sealing portion of the clapper.

To overcome many of the problems of leakage around the clapper of acheck valve, Scaramucci (U.S. Pat. No. 3,075,547) invented another sealarrangement for a clapper that seals both on a flat surface and aconical shaped surface. Such a seal required accurate machining of theconical shaped surface and the flat surface of the check valve body,plus accurate machining of the portion of the clapper holding the sealin position. The clapper also had to be very accurately suspended withrespect to the machined surfaces of the check valve.

Haenky, et al. (U.S. Pat. No. 3,068,903), which has the same assignee asthe present invention, shows a combination check and plug valve. Theclapper portion of the valve has a seal contained in a groove in theface of the clapper. To aid in the compressability of the seal to givemetal-to-metal contact, holes were formed along the center line of theseal as shown in FIGS. 9(a) and 9(b). In the prior patent issued toHaenky, et al., a problem of leakage at either low or high pressurefrequently occurred. Many times the leakage was around the back of theseal, rather than between the seal and the seal surface. The presentinvention may be used to make an improved clapper and clapper seal forU.S. Pat. No. 3,068,903, the incorporated reference.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved clapperfor check valves.

It is a further object of the present invention to provide a clapper forcheck valves having a seal with raised annular surfaces for sealingagainst the valve seat which seal has a web portion extending from theraised annular surfaces across the center surface of the clapper.

It is still another object of the present invention to provide animproved clapper for check valves with the improved clapper being formedfrom an investment casting.

By forming the clapper using investment casting, very accurate detailcan be obtained for the clapper. By cutting a reference plane surface onthe backside of the clapper, the clapper may be accurately positionedabout a centering hole. Thereafter, a bonded rubber seal may be formedon the face of the clapper with reference to the centering hole andreference plane. Raised annular surfaces of a seal extend upward from anannular groove in the face of the clapper. A web portion of the sealextends from the raised annular surfaces to cover the center surface ofthe clapper. The seal is bonded directly to the clapper face.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of the clapper.

FIG. 2 is an elevated view of the clapper face.

FIG. 3 is an enlarged view of the portion of FIG. 1 contained in circle"a".

FIG. 4 is a partial sectional view of the clapper sealing against avalve seat.

FIG. 5 is a partial sectional view of the clapper slightly raised off ofa valve seat.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Since U.S. Pat. No. 3,068,903 has been incorporated by reference, thedescription given hereinafter will be for a clapper that may be used inthe incorporated reference. Some of the numerals previously used in theincorporated reference will be used herein. All new component partsreferring to the clapper will begin with reference numeral 100, whichreference numeral represents the clapper generally.

Referring to FIGS. 1 and 2 in combination, the clapper 100 has agenerally flat circular body 102. The flat circular body 102 has a frontface 104 and a rear surface 106. Extending outwardly from the edge 108are mounting arms 110 with aligned holes 112 extending therethrough. Thealigned holes 112 are adapted to receive pivot pin 25 of the combinationvalve 1 (see incorporated reference).

In the front face 104 of the clapper 100 is located an annular groove114. The center surface 116 of front face 104 is recessed with respectto the front face 104. Located in the annular groove 104 is a seal 118.The seal 118 has a pair of spaced outwardly extending annular surfaces120 and 122, both of which extend beyond the front face 104. A centerweb 124 is bonded to the center surface 116 and is formed integral withthe entire seal 118.

The rear surface 106 of the clapper 100 has a slightly raised portion126. In the center of the rear surface 106 is located a centering hold128.

Referring to the enlargement shown in FIG. 3, the construction of theface of the clapper 100 can be better understood. While it is obviousthat the annular groove 114 extends into the flat circular body 102considerably below the front face 104 and center surface 116, otherdimensions may not be quite as obvious. For example, assuming that thefront face 104 is the base plane, the distance from the plane formed bythe front face 104 to the plane formed by the center surface 116 isdistance d₁. The distance from the plane formed by the front face 104 tothe outer surface of center web 124 is distance d₂, which is less thandistance d₁. The distance from the plane formed by front face 104 to theoutwardly extending annular surfaces 120 and 122 is distance d₃. Itshould be particularly noted that the center web 124 is recessed in theflat circular body 102 from the front face 104 by the distance d₂.

Referring now to FIG. 4, there is shown a partial sectional view of aclapper 100 mounted in the body 2 of the combination valve 1 of Haenky,et al (see incorporated reference). As the clapper 100 is pressedagainst the check valve seat 111 due to reverse pressure on the rearsurface 106, the outwardly extending annular surfaces 120 and 122 deforminward into the space therebetween. Because of the center web 124 of theclapper 100, reverse pressure cannot cause fluid leakage between therear of seal 118 and annular groove 114. Also, metal-to-metal contactexists between the check valve seat 111 and front face 104.Metal-to-metal contact is necessary to meet fire safety requirements. Bydeforming the outwardly extending annular surfaces 120 and 122 into thespace therebetween, a constant positive force can be exerted on theclapper 100 by the plug 3 (shown in incorporated reference).

The center web 124 provides additional strength for the seal 118, andalso provides abrasion resistance to fluid particles that may be flowingthrough the valve. Further, the center web does not allow any points ofentry of fluid behind the seal 118.

METHOD OF MANUFACTURING

Clappers, as previously described in Haenky, et al., were formed byeither forging, sand casting or dye casting. In any event, theuniformity of the dimensions of a clapper could only be insured byconsiderable machining of the alignment holes of the mounting arms andthe front face of the clapper. In the present invention, the clapper isformed by investment casting (also called "lost wax casting") to obtainaccurate cast detail for the clapper thereby requiring a minimum ofmachining. By forming clapper 100 using investment casting techniquesnot previously used in the manufacturing of check valves, only onesurface needs to be accurately cut relative to the aligned holes 112. Aflat surface is machined on the slightly raised portion 126 so that theflat surface is parallel to the axis of aligned holes 112.

By positioning the clapper 100 via the centering hole 128 on themachined, slightly raised portion 126, the seal 118 may now be formed.The seal 118 may be formed from any molded seal substance, such asrubber, on the front face 104 of clapper 100 in the position shown inthe drawings. By forming the seal 118 from molded rubber, the onlyflashing that will occur will be minimal and will be around the outeredge adjacent front face 104. No trimming of the seal 118 is necessaryprior to use of the clapper 100. The seal 118 is very accurately locatedwith respect to the machined, slightly raised portion 26 and alignedholes 112. Once the molded rubber seal has hardened, the clapper 100 isready for installation in a suitable valve, such as Haenky, et al.

We claim:
 1. A metal clapper to prevent reverse flow in a metal checkvalve apparatus, comprising:a metal clapper having a continuous metalannular sealing surface for sealingly engaging a continuous metalannular sealing surface on a check valve apparatus; said metal clapperhaving a continuous annular groove therein adjacent and surrounded bythe continuous metal sealing surface; a continuous web of resilientmaterial bonded to the clapper within the space surrounded by thecontinuous metal annular sealing surface and extending into the annulargroove to prevent any leakage around the annular groove; said centralweb being recessed from said annular sealing surface of said clapper;said central web having a raised annular seal formed of said resilientmaterial and extending from said groove past the clapper annular sealingsurface and deformably engageable with a check valve sealing surfaceupon engagement of the two metal sealing surfaces to prevent leakagearound the annular groove and flow through the check valve apparatus inone direction.
 2. The clapper as set forth in claim 1, wherein saidannular seal has a pair of raised annular sealing surfaces.
 3. Theclapper as set forth in claim 2, wherein: said raised annular sealingsurfaces have an annular recess therebetween to allow deformation ofsaid pair of raised annular sealing surfaces upon engagement with acheck sealing surface.
 4. A metal check valve apparatus having a metalclapper to prevent reverse flow, comprising:a metal clapper having acontinuous metal annular sealing surface for sealingly engaging acontinuous metal annular sealing surface on the check valve apparatus;said metal clapper having a continuous annular groove therein adjacentand surrounded by the continuous metal sealing surface; a continuouscenter web of resilient material bonded to the clapper within the spacesurrounded by the continuous metal annular sealing surface and extendinginto the annular groove to prevent leakage around the annular groove;said central web being recessed from said annular sealing surface ofsaid check valve apparatus; said central web having a raised annularseal formed of said resilient material and extending from said groovepast the clapper annular sealing surface and deformably engageable withthe check valve sealing surface upon engagement of the two metal sealingsurfaces to prevent leakage around the annular groove and flow throughthe check valve apparatus in one direction.
 5. The apparatus as setforth in claim 4 wherein said annular seal has a pair of raised annularsealing surfaces.
 6. The apparatus as set forth in claim 5, wherein saidraised annular sealing surfaces have an annular recess therebetween toallow deformation of said pair of raised annular sealing surfaces uponengagement with the check sealing surface.